Marten (Maarten) Schagen, born 24 October 1700, at Alkmaar, died 20 October 1770, at Utrecht, was a son of Pieter Martens Schagen and Grietje Jacobs Volder. He was baptized in Alkmaar (Frisian congregation) in 1718 and in the same year he moved to Amsterdam, where he opened a bookstore and a publishing house on the Nieuwedijk in 1723. He printed and published a number of books, the most outstanding of which was a Dutch translation of the works of Josephus by A. Loosjes and J. L. Rogge in 1732. In the meantime he made a thorough study of languages (German, French, Latin, even Greek and Hebrew), literature, and theology. In 1727 he was called to be a (unsalaried) preacher of the Frisian congregation (Arke Noach) at Amsterdam, serving here until 1738, at the same time running his business. In October 1737 he took the initiative in holding weekly meetings in a room of the church to explain and discuss the New Testament. In 1738 he was called to serve the Waterlander and Frisian congregations (then united) at Alkmaar (salary 750 Dutch guilders; 1,000 guilders after 1739); he served here only three years, in 1741 accepting a call from the Utrecht congregation, which he served until his death. By his activity, his wise policy, and his strong faith he succeeded in raising the Utrecht congregation, which had fallen into a serious decline, to great prosperity. After his death his colleague Joannes Cuperus delivered a funeral sermon in his memory - M. Schagen . . . plegtig gedagt in eene Lykrede (Utrecht, 1770), in which both his assiduity and his tolerance are highly praised.

But Schagen's special interest in study was church history. In this field he published a book on the Waldenses, Historie der Christenen, die men gemeenlyk Waldensen noemt tot den Jaere 1200 (Amsterdam-Haarlem, 1732, reprinted 1765, 1769), and two apologetical books on the Dutch Mennonites: De Kerk der Nederlandsche Doops-gezinden in derzelver Reformatie vertoont, three sermons (Haarlem, 1743), and De Reformatie der Nederlandsche Doops-gezinden, en deselve met de Kerkhervorming in't gemeen tegen alle Bezwaering verdeedigt (Haarlem, 1744). A book which is still of great value is the translation by Schagen of S. F. Rues' Aufrichtige Nachrichten von dem gegenwärtigen Zustande der Mennoniten oder Taufgesinnten wie auch der Collegianten oder Reinsburger in den vereinigten Niederlanden (Jena, 1743), which with numerous notes and corrections by Schagen was published under the title Tegenwoordige Staet der Doopsgezinden of Mennoniten in de Vereenigde Nederlanden (en) een Berigt van de Rynsburgers of Collegianten (Amsterdam, 1745). The additions by Schagen give the translation superiority over the original edition. In 1745 Schagen published a bibliography containing the names of Mennonite authors and their books with exact annotations, mentioning all reprints. Of this valuable book, entitled Naamlijst der Doopsgezinde Schryveren en schriften van 1539-1745 (Amsterdam, 1745), the Amsterdam Mennonite Library has a copy, in which Schagen himself annotated new editions and reprints published after 1745.

Schagen possessed a rich library of Mennonite books including many rare editions, which he bequeathed to the congregation of Utrecht; the catalogue of this library numbers 72 pages. In 1834 the books were sold for 250 Dutch guilders to the [[Amsterdam Mennonite Library (Bibliotheek en Archief van de Vereenigde Doopsgezinde Gemeente te Amsterdam)|Amsterdam Mennonite library]], where they are at present. The Amsterdam Mennonite archives also contain a handwritten copy of a sermon by Schagen on Matthew 22:31-32 and also a number of historical annotations made by himself, including the manuscript of his translation of Rues’ book.